consider support for np 1.13 __array_ufunc__

[gdementen]

numpy/numpy#8247

[alixdamman]

The idea is to be able to do something like that:

arr = ndtest((3, 3))
np.sum(arr)

?

[gdementen]

I don't remember exactly. But it was indeed to improve interoperability with numpy ufuncs in general.